After 12 years of trying, Mark Dempsey, Fowler, IL, finally won first place in the National Corn Growers Association AA non-irrigated corn yield contest, with a 348.3748-bu./acre yield.

The key to this year's win was plentiful rainfall, says Dempsey, who grows corn, soybeans and hay in the west-central portion of the state, near Quincy. “I placed second nationally in 2004 with a 320-bu. yield,” he points out. “Then in 2005, 2006 and 2007 we had three drought years in a row. Basically, last year I had double the rainfall that I'd had in 2005, 2006 and 2007 combined.”

In addition to receiving ample rains, winning a yield contest takes a lot of hard work, says Dempsey, who won the 2008 contest with a Garst 8488IT corn hybrid. “I scout my contest plot about 30-40 times during summer,” he points out. “I've also been willing to change and to try new things.”

INSTALLING DRAINAGE TILE on half the 63-acre farm that won the contest plot in 2008 was especially helpful, he reports. “The difference between the tiled and non-tiled ground was about 100 bu./acre last year,” he says. “The tiled ground averaged more than 300 bu./acre and the non-tiled ground averaged 208 bu./acre. So, I just finished tiling the other half of that farm with a 3-in. tile on 40-ft. centers in December.”

Ample nutrient applications are also necessary to obtain high yields, he points out. “I usually put about 260 units of nitrogen (N) on my contest plot,” says Dempsey. “Last year, I was only at 240 units, because it was too wet to put on a liquid N application after the corn came up.”

Obviously, timing can also make a big difference, he adds. “I do 100% spring N applications, mostly with preplant anhydrous,” says Dempsey. “I think you lose too much N with a fall application. Even with spring applications, I saw a little N deficiency on one hybrid this year due to all the rain.”

PLANT POPULATIONS ARE another area where Dempsey refuses to cut back, especially on his yield-winning contest plots, which are in continuous corn. “I push my contest fields to about 44,000 plants/acre on 30-in. rows,” he says. “My contest field is nine years into continuous corn. You'll take a yield reduction after your second year and maybe a little after your third year. Then after that, the yields go back up.”

Deep tillage is another reason for his high yield. “On my darker, prairie soils, I've gone to a mini-moldboard plow that runs 16-18 in. deep,” says Dempsey. “This allows the roots to get down to the moisture faster, especially in a dry year. The deep tillage also promotes quicker, early growth.”

With the high plant populations and heavy crop residue from continuous corn, Dempsey says he's found that working the plant matter deeper into the soil helps to keep yields up. Yet, even with the mini-moldboard, he's still able to leave 30-40% crop residue on the soil surface for conservation compliance.